usually it takes two people.. one to hold and to move the door up and down slightly in the open position .. the other to either unlatch the end of the (as nissan calls it.. STAY ASSY-BACK DOOR) then probably unscrew the captured ball end on the other end.. use extreme care that when you are starting the threads in the new one.. that you get them lined up straight. without weight on them so they go in without cross threading.. then latch the ball end in..

there are several ways to do it..

you also might want to check with nissan parts.. as the pricing i saw online.. might be significantly less than many parts stores..

i don't see them cataloged yet at least at AZ... oe fit is usually better..

Lift Support is what they are called in parts stores

or Charged lift supports ...

strong arms is one brand that is also a noun used in describing them..